The present invention relates to a liquid crystal display device used to display time information for a timepiece such as hours, minutes, and seconds and calendar information such as date, a day of the week, month, and year in digital form, using a liquid crystal display panel, or to display information from a microcomputer, a memo or the like, or to display information upon receiving a signal from the outside.
There exist various electronic equipments and devices to display, using a liquid crystal display panel, time information such as hours, minutes, and seconds, or a memorandum or other information, utilizing memory in a microcomputer such as a PC (a personal computer), a handy computer, a PDA (a personal data assistant), a digital camera, a cellular phone or the like having a communication function.
The liquid crystal display panel in the liquid crystal display device used for these electronic machines and devices can be broadly classified into two groups. One includes liquid crystal display panels using a polarizing film and the other includes types of liquid crystal display panels not using a polarizing film. The present invention relates to a liquid crystal display panel using a combination of a liquid crystal cell with a polarizing film.
Conventionally, this kind of liquid crystal display device performs display by voltage control of the transmission and absorption of light through a liquid crystal layer and a polarizing film.
Here, an example of a conventional liquid crystal display device to display information in digital form will be explained with reference to drawings.
FIG. 17 is a perspective view of a conventional liquid crystal display device used to perform the display of data. FIG. 18 is a schematic sectional view taken along the line 18xe2x80x9418 in FIG. 17. FIG. 19 is an enlarged sectional view of a portion in the liquid crystal display panel in FIG. 18.
A liquid crystal display panel 300 used in this liquid crystal display device includes, in order from the side of glass 2 shown in FIG. 18 (the side visible to a viewer), a first substrate 11, a first electrode 12, a second substrate 13 facing the first substrate 11 at a predetermined distance, and a second electrode 14 provided on the second substrate 13, wherein a portion where the first electrode 12 and the second electrode 14 overlap one another serves as a display pixel.
The first electrode 12 and the second electrode 14 are striped electrodes and are in a matrix-type display pixel arrangement.
A liquid crystal layer 15 exists between the first substrate 11 and the second substrate 13, and the liquid crystal layer 15 is sealed with a sealing agent 33 and a sealant.
An alignment layer is provided on the first substrate 11 and the second substrate 13 to align the liquid crystal layer 15 in a predetermined direction.
For instance, in the case of a twisted nematic liquid crystal, the liquid crystal layer 15 aligns in the direction corresponding to the time 7:30 on the first substrate 11 side, and the time 4:30 on the second substrate 13, and has a twist angle of 90xc2x0. When the capacity of data display is required large, a super twisted nematic liquid crystal having an enlarged twist angle from 210xc2x0 to 260xc2x0 is sometimes used.
A first polarizing film 21 consists of an absorption-type polarizing film on which a coloring agent is spread in the one direction is provided on the first substrate 11, and a second polarizing film 22 consists of, for example, DBEF (trade name) made by Sumitomo 3M Co., Ltd. is provided as a reflection-type polarizing film on the second substrate 12.
The transmission axes of the first polarizing film 21 and the second polarizing film 22 are disposed parallel with each other and by combination with a liquid crystal panel, a strong reflection state can be shown when the voltage applied to the liquid crystal layer 15 is low, and a transmission state can be shown when the applied voltage is high.
Below the liquid crystal display panel 300, a light source 7 consisting of an electroluminescent element (EL) is provided, and a printed circuit board 5 to apply a predetermined voltage to the liquid crystal display panel 300 and the light source 7 is provided.
On the first substrate 11 forming the liquid crystal display panel 300, an integrated circuit (IC) 96 comprising a driver circuit to drive a liquid crystal display panel is provided and a flexible printed circuit (FPC) 36 is used to connect the printed circuit board 5 and the liquid crystal display panel.
The printed circuit board 5 and the light source 7 are connected through a terminal for a light source (not shown).
The liquid crystal display panel 300 is held with a panel stopper, and is connected to the printed circuit board 5 and the like with a circuit board stopper holding the printed circuit board 5 and the like.
On the side face of the printed circuit board 5, a battery 6 is connected by means of a battery stopping spring 38.
A liquid crystal display device module consisting of the liquid crystal display panel 300 and the printed circuit board 5 is housed in the inside of a case 1 of the liquid crystal display device, having a glass 2 and a case back 3.
The liquid crystal display device having such a structure has a display section 41 shown in FIG. 17, and the display section 41 has a input-letter display section 48 which makes it possible to input on the liquid crystal display panel with an input-pen 10. The liquid crystal display device also has a series of control switches to display information necessary to a viewer.
The liquid crystal display device is provided with buttons such as scroll (+), (xe2x88x92) buttons 51 and 52 to scroll the display, a display mode shifting button 53, and an electric power switch 54 and with a speaker 40 for acoustic information. These control switch or buttons are mounted on a switch board 70 shown in FIG. 18 and are connected with the printed circuit board 5 through a FPC 71.
The display of only the data alone imparts a monotonous design, and further lacks an interesting feature, which leads to loss of popularity among customers.
As is shown in the conventional example, even when a metallic display can be realized by applying a reflection-type polarizing film, a liquid crystal display device which can perform a data display in a variety of designs has been still required.
A method of shielding (opening and closing of a shutter) a portion or all of the data-display section of the liquid crystal display device in accordance with circumstances at the time of use or internal condition of the liquid crystal display device has been studied, but it can not be said sufficient with regard to making the liquid crystal display device thinner and controllable.
It is also required that the closing and opening of a time-display section can be performed by a liquid crystal display device user, a timer, or a signal from the outside through communication, or that display or no display of information can be carried out by using a portion of the time-display section itself as a shutter. However, the above design challenges of such a liquid crystal display device have not been solved.
An object of the present invention is to solve the disadvantages described above and provide a digital-type liquid crystal display device having a variety of designs. Another object of the present invention is to improve the design and provide a variously configurable liquid crystal display device, wherein the time-display section can be closed or opened in accordance with circumstances where the liquid crystal display device is in use, a control signal from a user, or internal conditions of the liquid crystal display device.
To achieve the above described object, a liquid crystal display device according to the present invention is comprised of laminated plural liquid crystal display panels, each of which comprises a liquid crystal layer filled in a gap between a pair of transparent substrates which provide an electrode on each opposing inner surface, and a reflection-type polarizing film which transmits the light linearly polarized in the direction parallel to the transmission axis thereof and reflects the light linearly polarized in the direction orthogonal to the transmission axis thereof, is disposed on at least any surface among the top surface of the plural liquid crystal display panels, between liquid crystal display panels, and the bottom surface of the plural liquid crystal display panels.
Especially, it is preferable that two of the above described liquid crystal display panels are laminated in such a manner that at least a portion thereof is overlaped each other, and the above described reflection-type polarizing film may be disposed at any one position among the top surface of the two laminated liquid crystal display panels, between the two laminated liquid crystal display panels, and the bottom surface thereof.
In such a case, it is desirable to dispose the above described reflection-type polarizing film between the two laminated liquid crystal display panels, i.e., each one of the two liquid crystal display panels has an inner substrate facing the other liquid crystal display panel and an outer substrate placed opposite the other liquid crystal display panel, and the reflective-type polarizing film is disposed between the inner substrates of the two liquid crystal display panels.
The reflection-type polarizing film is preferably disposed in such a manner that the reflection-type polarizing film is adhered to the inner substrate of one of the liquid crystal display panels and a predetermined gap is provided between the reflective-type polarizing film and the inner substrate of the other liquid crystal display panel.
The gap between the above described reflection-type polarizing film and the inner substrate of the other liquid crystal display panel can be formed with a printed layer provided around the display area of the liquid crystal display panel.
A liquid crystal display device according to the present invention can be structured in such a manner that two of the above structured liquid crystal display panels are laminated so that at least a portion thereof is respectively overlaped each other, and a first polarizing film is disposed on the top surface of the two laminated liquid crystal display panels, a second polarizing film is disposed between the two liquid crystal display panels, and a third polarizing film is on the bottom surface, respectively.
Alternatively, a plurality of the above-described reflection-type polarizing films can be disposed.
It is preferable that the top surface of the laminated two liquid crystal display panels is placed on the visible side, and that the first polarizing film is an absorption-type polarizing film to transmit the light linearly polarized in the direction parallel to a transmission axis thereof but to absorb the light linearly polarized in the direction orthogonal to the transmission axis thereof, the second polarizing film is a reflection-type polarizing film, and the third polarizing film is a combination of a light-diffusion layer and the reflection-type polarizing film.
In addition, it is preferable that the first polarizing film, the second polarizing film, and the above described liquid crystal display panel disposed in between, are arranged to have a high transmission characteristic, as opposed to having a high reflection characteristic, in relation to a viewer side, when a voltage applied to the liquid crystal display panel is increased.
It may also be preferable, on the contrary, that the first polarizing film, the second polarizing film, and the liquid crystal display panel disposed in between are arranged to have a high reflection characteristic, as opposed to having a high transmission characteristic, in relation to the viewer side, when a voltage applied to the liquid crystal display panel is increased.
When the high reflection characteristic is shown in relation to the viewer side by the above described first polarizing film, the second polarizing film, and a first liquid crystal display panel disposed in between, low voltage is preferably applied to a second liquid crystal display panel.
Alternatively, in a liquid crystal display device according to the invention, two liquid crystal display panels structured as described above are laminated in such a manner that at least a portion respectively of the two liquid crystal panel is overlaped each other, a first polarizing film is disposed on the upper surface of the first liquid crystal display panel disposed on the viewer side of the laminated two liquid crystal display panels, a second polarizing film is disposed between the first liquid crystal display panel and the second liquid crystal display panel, that is the other liquid crystal display panel, and the third polarizing film is disposed on the bottom surface of the above described second liquid crystal panel, respectively.
The first liquid crystal display panel has a plurality of segment display sections, and when the display shows a high transmission characteristic with the first polarizing film, the second polarizing film and the first liquid crystal display panel, the portion between each segment display section of the first liquid crystal display panel has a steady section in which a high reflection characteristic is constantly maintained when no voltage is applied to the liquid crystal layer.
The second liquid crystal display panel has a display pixel consisting of a matrix-type electrode structure. The display pixel of the second liquid crystal display panel is smaller than the above-described steady section, and a font size displayed by the second liquid crystal display panel can be made larger than the steady section of the first liquid crystal display panel.
Furthermore, a reflection-type polarizing film is disposed between the first liquid crystal display panel and the second liquid crystal display panel, an optical power-generating element which generates electric power on exposure to light is disposed on the bottom side of the second liquid crystal display panel, viewed through the polarizing film, and the display is performed on the first liquid crystal display panel or on the second liquid crystal display panel by means of light having a wavelength area contributing to the power generation of the optical power-generating element so that the electric power generated by the optical power-generating element can be used for power to drive the first and second liquid crystal display panels.
In such a case, a light scattering layer is preferably disposed between the optical power-generating element and the second liquid crystal display panel.
A light-wavelength conversion layer, which absorbs short wavelength light and emits long wavelength light, can be arranged between the above described optical power-generating element and the second liquid crystal display panel.
A liquid crystal display device according to the present invention has at least any one of a sensor which detects a control signal generated by a viewer (user), a sensor to detect the circumstances of use, and a sensor to detect the time at which the liquid crystal display device displays, and a ratio of light incident on the transmission axis of the reflection-type polarizing film to light incident on the reflection axis intersecting the transmission axis at right angles can be varied by the liquid crystal display panel in accordance with a signal output by the sensor.
Alternatively, a sensor which detects a radio wave signal existing in the applied circumstance may also be provided, and in accordance with the signal detected by the sensor and an output signal therefrom, a ratio of light incident on the transmission axis to the light incident on the reflection axis orthogonal to the transmission axis can be varied by the liquid crystal display panel.
The application of voltage to the liquid crystal layers of the above described plural liquid crystal display panels is periodically and continuously conducted and the content displayed on each liquid crystal display panel is slightly shifted so that a three dimensional display can be performed, by means of a positional difference in the laminating direction of each liquid crystal display panel and the deviation of the display.
It is preferable to provide a light source, which emits light upon application of voltage thereto, on the bottom side of the lowest surface of the plural liquid crystal display panel. In such a case, the liquid crystal display panel can be driven in synchronization with the light source.
Alternatively, a fluorescent ink layer which emits light by absorbing light and changing the wavelength thereof can be provided on any place among the light source, on the polarizing film in the lowest layer, or between the above described light source and the polarizing film.
Furthermore, it is preferable to provide a light-diffusion layer consisting of a spacer on at least any one of the bottom side and the top side of the above described reflection-type polarizing film so that the reflection-type polarizing film and a opposing substrate form a gap with the spacer.